Effective methods for the recovery and/or separation of particular ions such as ruthenium, palladium, gold, silver, and mercury ions in either cation or complex anion form from solutions thereof, admixed with chelating agents and/or other ions which may be present, represent a real need in modern technology. As specific examples, efficient and economical separation of (1) small amounts of Ru, Pd, Au, Ag, from industrial concentrates; (2) separation of Ru, Pd, Au, and Ag, from solutions containing large amounts of base metals; and (3) separation of Hg as toxic wastes from acidic solutions, all represent real separation needs with presently either unsatisfactory technologies for their accomplishment, or for which more economical technologies are desired. These ions are often present at low concentrations in solutions containing other ions at much greater concentrations. Hence, there is a real need for a process to selectively concentrate and recover these ions.
The fact is known that macrocyclic polythioethers and certain other sulfur-containing hydrocarbon ligands present as solutes in a solvent such as water are characterized by their ability to selectively form strong bonds with the noble metal, platinum group metal, and mercury ions or groups of these ions present as solutes in the same solvent as described in articles by R. M. Izatt, et al. A CALORIMETRIC TITRATION STUDY OF UNI-AND BIVALENT METAL ION INTERACTION WITH SEVERAL THIA DERIVATIVES OF 9-CROWN-3, 12-CROWN-4, 15-CROWN-5, 18-CROWN-6, 24-CROWN-8 AND WITH SEVERAL OXATHIAPENTADECANES IN WATER OR WATER-METHANOL SOLVENTS AT 25.degree. C., Inoroanica Chemica Acta. 30:1-8 (1978) for the complexation of silver and mercury ions by open chain sulfur-containing hydrocarbons and by S. R. Cooper, CROWN THIOETHER CHEMISTRY, Accounts of Chemical Research. 21:141-146 (1988) for the complexation of rhodium and silver ions by macrocyclic sulfurcontaining ligands.
Articles such as those entitled SILANE COMPOUNDS FOR SILYLATING SURFACES by E. P. Plueddemann, in "Silanes, Surfaces and Interfaces Symposium, Snowmass, 1985," Ed. by D. E. Leyden, Gordon and Breach, publishers, pp. 1-25 (1986) and SILANE COUPLING AGENTS by E. P. Plueddemann, Plenum Press, pp. 1-235 (1982) list many different types of organic materials which have been attached to silane compounds and discuss some of their properties.
Bradshaw, et al., U.S. Pat. No. 4,959,153 describe certain sulfur containing hydrocarbons covalently bonded to a hydrophilic solid support which can be used to selectively bind noble and platinum group metals as well as some transition metals. In many cases these prior art sulfur-containing hydrocarbons can be eluted using one or two eluents such as amines or CN.sup.- which are not always desirable eluents.
These prior art compositions do not provide the means for selecting the desired interactive strength between the ions to be removed and the ligands to which they are to be bound for removal. Hence the sought for selectivity for ion removal and subsequent elution from the binding ligands is not always achieved.
The compositions described herein accomplish these desirable objectives by a controlled reduction of the interaction strength via the appropriate addition of electron withdrawing groups of varying strength.